BRITAIN is now paying a terrible price for the self-destructive policies of multi-culturalism and mass immigration.

Due to these twin ideologies we are now confronted by the deadly menace of militant Islam within the heart of our society. In the name of diversity and tolerance, the state has allowed barbaric intolerance to flourish in our midst.

The lethal danger from jihadism has been graphically highlighted by the growing number of Muslims from Britain now fighting in Syria and Iraq. The police have estimated that more than 500 young radicals from our shores have travelled to the Middle East to join extremist groups such as the Islamic State of Iraq and the Levant (ISIS), a notoriously savage organisation that wants to create a despotic medieval caliphate.

In addition, around 300 jihadists are thought to have returned to Britain after involvement in terrorist campaigns in Syria and Iraq, posing a lethal threat to the fabric of our civilisation. According to Richard Barrett, the former head of counter-terrorism at MI6, the sheer number of these returning zealots means that it would be "a completely impossible task" for our security forces to keep track of all of them.

The British Muslim link to jihadism was further emphasised over the weekend when a group of Islamists from Britain put a recruitment video online, urging young Muslims to join them in the fight with ISIS. "What prevents you from obtaining martyrdom and the pleasure of your lord?" asks one of the group. He has subsequently been identified as Reyaad Khan, a 20-year-old from Cardiff.

THE mounting evidence of home-grown jihadism has led to a predictable bout of hand-wringing and self-flagellation from left-wing commentators.

"Why do these young men feel so alienated from British society?" they ask in bewildered tones. But there is nothing incomprehensible about the actions of the British jihadists. They are just doing the same as Muslim extremists all over the world, following a vile political ideology. In their eager embrace of the blood soaked horror of ISIS, they are no different from the butchers of Drummer Lee Rigby or the kidnappers of schoolgirls in Nigeria, or the misogynist Taliban brutes of Afghanistan or the Islamic death squads in Somalia.

The British state, especially under Tony Blair, pretended that militant Islam could be contained at home by fighting it abroad but that was a complete fallacy. Our interventions in Afghanistan, Iraq and Libya have only succeeded in fuelling extremism within Britain, whipping up jihadists to new heights of self-righteous fury.

Their allegiance is to hardline doctrine

Another great fallacy of the progressive interventionists is that the flames of extremism can be extinguished by westernised education. But that is more wishful thinking. Just like the July bombers of 2005, all the British jihadists in the Middle East went through our schools system, yet still emerged as radicals.

But by far the worst error has been the state's addiction to immigration and multiculturalism. Domestic jihadism is the direct creation of a political class obsessed with open borders and the transformation of our society's structure. Thanks to these two strategies, the Muslim population of Britain has now reached almost three million, while one in 10 British children under the age of four is Muslim. The pro-immigration brigade tells us that this is no problem, since the "vast majority" of Muslims are moderate. But that is more self-deceit at odds with the evidence. One independent survey showed that 40 per cent of Muslims here want to live under Sharia law; another revealed that 32 per cent of Muslim students at university felt killing in the name of religion is justified.

Such attitudes have been reinforced by the state's fixation with cultural diversity which, instead of promoting integration, encourages migrant groups to cling to their traditional customs, practices, even languages. That is how we have ended up with Muslim enclaves dominated by the burkha, sharia tribunals, forced marriages, and ballot box fraud. Nor do the mosques do much to promote social cohesion. A recent study found that, out of Britain's 1,700 mosques, just two follow a modernist interpretation of the Koran, while a quarter do not even allow women on the premises.

And the truth is that Islamic extremists have contempt for our society. Their allegiance is entirely to their hardline doctrine, not to this country.

INDEED, it is absurd to describe them as "British" at all, for they have complete disdain for the normal responsibilities of British citizenship.

They are interested only in exploiting us, whether it be through welfare or education or housing or legal aid.

The political class has appeased radical Islam for far too long. The militants have only been emboldened by this stance, recognising it as weakness dressed up as tolerance. If we are to conquer the enemy within, that means getting far tougher with the extremists. Jihadists with only limited connections to Britain should be stopped from re-entering the country by the withdrawal of their passports. And those who make it back should face long sentences for terrorism and treachery.

But we would not be in this mess if our rulers had decided to protect our society instead of feebly colluding with our enemies.